Emmy Rossum Packs a Pistol for New Role

"It was really fun," the Golden Globe-nominated actress-singer, 21, told PEOPLE at Saturday's alice+olivia Perrier Jouet-hosted Hamptons fashion show, where she showed support for her friend Stacey Bendet's women's fall collection. "I still have my papers from the target practice at home, because I was just so proud that I could shoot it."

Besides firing bullets, the Day After Tomorrow and Poseidon star also did a lot of strength training and kickboxing to shape up for Dragonball, which is based on the Japanese manga series.

"I got really buff and strong while training," said Rossum, noting that her weight didn't change but the tightness of her body did. Rossum called her workout "hardcore, but it was a lot of fun."

As for the rest of her summer, now that she's finished shooting the indie drama Dare and started her second recording for Interscope, Rossum says, "I'm hoping to spend some time in the Caribbean, or maybe I'll go to Greece."